Neeb Daniel, Kunz Rainer Peter, Ley Sebastian, Szábo Gábor, Strauss Ludwig G, Kauczor Hans-Ulrich, Kreitner Karl-Friedrich, Schreiber Laura Maria
Department of Radiology, Johannes Gutenberg-University Medical School, Mainz, Germany.
Magn Reson Med. 2009 Aug;62(2):476-87. doi: 10.1002/mrm.22025.
Validation of quantification of pulmonary blood flow (PBF) with dynamic, contrast-enhanced MRI is still missing. A possible reason certainly lies in difficulties based on the nonlinear dependence of signal intensity (SI) from contrast agent (CA) concentration. Both aspects were addressed in this study. Nine healthy pigs were examined by first-pass perfusion MRI using gadolinium diethylenetriamine pentaacetic acid (Gd-DTPA) and H(2)(15)O positron emission tomography (PET) imaging. Calculations of hemodynamic parameters were based on a one-compartment model (MR) and a two-compartment model (PET). Simulations showed a significant error when assuming a linear relation between MR SI and CA dose in the arterial input function (AIF), even at low doses of 0.025 mmol/kg body weight (BW). To correct for nonlinearity, a calibration curve was calculated on the basis of the signal equation. The required accuracy of equation parameters (like longitudinal relaxation time) was evaluated. Error analysis estimates <5% over-/underestimation of the corrected SI. Comparison of PET and MR flow values yielded a significant correlation (P < 0.001) in dorsal regions where signal-to-noise ratio (SNR) was sufficient. Changes in PBF due to the correction method were significant (P < 0.001) and resulted in a better agreement: mean values (standard deviation) in units of ml/min/100 ml lung tissue were 59 (15) for PET, 112 (28) for uncorrected MRI, and 80 (21) for corrected MRI.
动态对比增强磁共振成像对肺血流量（PBF）定量的验证尚付阙如。一个可能的原因肯定在于基于信号强度（SI）与造影剂（CA）浓度的非线性依赖关系所带来的困难。本研究探讨了这两个方面。使用钆二乙三胺五乙酸（Gd-DTPA）和H₂¹⁵O正电子发射断层扫描（PET）成像，对9只健康猪进行首过灌注磁共振成像检查。血流动力学参数的计算基于单室模型（MR）和双室模型（PET）。模拟显示，即使在0.025 mmol/kg体重（BW）的低剂量下，假设动脉输入函数（AIF）中MR SI与CA剂量之间存在线性关系时，也会出现显著误差。为校正非线性，基于信号方程计算了校准曲线。评估了方程参数（如纵向弛豫时间）所需的精度。误差分析估计校正后的SI高估/低估<5%。PET和MR血流值的比较在信噪比（SNR）足够的背侧区域产生了显著相关性（P < 0.001）。校正方法导致的PBF变化显著（P < 0.001），并产生了更好的一致性：以ml/min/100 ml肺组织为单位的平均值（标准差），PET为59（15），未校正的MRI为112（28），校正后的MRI为80（21）。
